Corrosion-resisting lubricating compositions



Patented Oct. 18, 1949 CORBOSION-RESISTING LUBRICATING COMPOSITIONS Frank J. Glavls, Elkins Park, and Harry T.'Neher,

Bristol, Pa., assig'nors to R hm & Haas Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Application February 13, 1947, Serial No. 728,388

This invention relates to lubricating compositions comprising diesters of dicarboxylic acids and saturated aliphatic alcohols to which are added .in minor amounts an oil-soluble petroleum sulfonate and an alkylphenyl polyethoxyethanol having three to five ether linkages.

The quest for liquid lubricants which have high boiling points, low vapor pressures at normal operating temperatures, and low freezing points-has led to a proposal to use esters of such dicarboxylic acids as sebacic acid. These esters are thin, light oils with favorable viscosity-temperature relationships. They do not provide the protection from corrosion due to moisture, vapor, water, or aqueous solutions which is required in practical applications. For example, polished steel plates covered with a film of such ester will begin to rust in one to three hours when exposed to warm, moisture-saturated air. While considerable improvement may result from the addition of conventional anti-rust agents, such as petroleum sulfonates, the resulting compositions do not exhibit uniformity of behavior and are not sumciently effective against moisture vapor and aqueous solutions to be entirely satisfactory without resort to such high proportions of additive as to alter the fundamental and desired characteristics of the base fluid.

It has now been found that compositions suitable for instrument lubricants, lubricants for high-speed machinery, valve lubricants, hydraulic fluids for transmitting pressure andpower, and base fluids for low-temperature greases are prepared from diesters of saturated aliphatic dicarboxylic acids of six to ten carbon atoms and saturated monohydric aliphatic alcohols of four to fourteen carbon atoms, in which compositions there are dissolved from 1% to 7.5%, preferably 8 Claims. (01. 25.2-43.4)

2.5% to 6.5%, of an oil-soluble petroleum sulfonate of high molecular weight and from about 0.5% up to 2% of an oil-soluble, water-insoluble polyether alcohol of the formula R-phenyl-(OCHzCHzMOCHaCHaOH I where n is an integer from two to four and R uniform results, good protection of metals from corrosion, and improved lubricating action with retention of low-temperature characteristics.

As diesters there may be used one or more of the compounds of the formula ROOQ-Z-COOR wherein Z is an alkylene chain of four to eight carbon atoms and R is an alkyl group of four to fourteen carbon atoms, being the residue of an aliphatic monohydric alcohol from butyl to tetradecyl alcohols. Dicarboxylic acids which provide the above esters are adipic, pimelic, suberic, azelaic,.and sebacic. The alcohols include butyl, isobutyl, or sec-butyl alcohols and the various amyl, hexyl, octyl, nonyl, decyl, undecyl, dodecyl, and tetradecyl alcohols. The alcohols with branched hydrocarbon chains provide diesters with particularly desirable properties. Typical of these are isobutyl, 2-ethylbutyl, Z-ethylhexyl, l-methylhexyl, gl-methylhe'ptyl, 1- methyl-4-ethylocty1, 2,2,4-trimethylhexyl, 2-isopropyl-3,3-dimethylbutyl, 1,4-dimethylbutyl, and 1-isobutyl-4-ethyloctyl alcohols.

The oil-soluble petroleum sulfonates, obtained from petroleum by treatment with sulfuric acid, oleum, or like compound, are used in the form of their alkali or alkaline earth salts, including the lithium, sodium, potassium, calcium, stronlation, from 2.5% to 6.5% of an oil-soluble petroleum sulfonate may be used, the amount being determined by the type and severity of conditions to be met. Where conditions are relatively favorable, somewhat less sulfonate may be used, and amounts of petroleum sulfonate down to 1% in conjunction with about one-half percent of one of the defined alkylphenyl polyethoxyethanols may be used. The upper ranges of petroleum sulfonate and alkylphenyl polyethoxyethanols are particularly helpful in preventing corrosion of metals by condensed moisture and by solutions of electrolytes.

Some typical compositions of this invention are showniin the following examples:

Erample 1 panels had started to rust. At the end of twentyi'our hours, the immersed panels were very badly corroded.

(b) A solution oi 2.5% of a sodium petroleum Within three hours. all tion No.

sulfonate of amolecular weight of about five hundred was made in dibutyl sebacate. Steel panels were coated with this solution and submitted to tests both in the humidity cabinet at 120 F. and in synthetic sea water. Within thirtytwo hours, thepanels in the cabinet had rusted. The corrosion of the immersed panels was bad at the end of twenty-four hours.

(c) A solution of 2.5% of the same sulfonate used above and 0.5% of octylphenoxy(ethoxy)4- ethanol in dibutyl sebacate was applied to steel panels which were tested both in the humidity cabinet at 120? F. and in synthetic sea water. Rusting was not observed until seventy-six hours of exposure to moisture. A very definite improvement was obtained in the immersion tests in synthetic sea water over the comparable tests reportedabove where the ether alcohol was not used. v

(d) A solution'of 2.5% of. the sulfonate used above in dibutyl sebacate was modified with 1% of octylphenoxy(ethoxy) iethanol and was applied to panelsv in the same .way as above. No rust appeared on the panels in the humidity cabinet until 112 hours had passed. After twenty-four hours of immersion in synthetic 'sea water, but slight corrosion was evident.

(e) To a solution of 2.5% of the same sulfonate,

in dibutyl sebacate was added 1% of diisobutylphenoxy(ethoxy) zethanol. This solution was applied to steel panels which were tested both in the humidity cabinet at 120 F. and in synthetic sea water. No corrosion was observed on the panels in the cabinet until 143 hours ,had passed. The protection of the immersed panels was rated as fair. They showed a considerable improvement over the panels coated with the sulfonate solution lacking the ether alcohol and immersed for twenty-four hours in synthetic sea water.

(f) A solution of 5.0% of a calcium petroleum sulfonate and 1% of butylphenoxy(ethoxy) 2- ethanol in dibutyl sebacate gave full protection to steel panels for over 168 hours in the humidity cabinet at 120 F. Panels coated with this composition and immersed in synthetic seawater are fairly well protected for twenty-four hours.

Without the ether alcohol, the panels rust rapidly upon immersion.

The synthetic sea water used in the tests described here was prepared so as to resemble as nearly as possible natural sea water as to salts or ions present, concentration of electrolytes, and value of pH. For this purpose, there was prepared Stock Solution No. 1 by dissolving in water 3885 grams of magnesium chloride hexahydrate, 406 grams of calcium chloride (anhydrous), and fourteen grams of strontium chloride hexahydrate and adjusting the solution to a volume of seven liters. Stock Solution No. 2 was made by dissolving in water 483 grams of potassium chloride, 140 grams of sodium bicarbonate, '70 grams of potassium bromide, twenty-one grams of boric acid, and 2.1 grams of sodium fluoride and adjusting the resulting solution to a volume of seven liters. A solution was made from 245.4 grams of sodium chloride and 40.9 grams of sodium sulfate in several-liters of water. Thereto was added two hundred milliliters of Stock Solution No. 1 and one hundred milliliters of Stock Solu- 4 2. The solution was then diluted to ten hters and adjusted with'a few milliliters of 0.1 molar sodium carbonate solution to a pH of 7.8.

Example 2 (a) Steel panels were immersed in pure di-secbutyl sebacate, drained, and hung in a humidity cabinet at F. Within three hours, the panels had started to rust. Other panels immersed in synthetic sea water rusted rapidly, and by the end of twenty-four hours were very badly corroded.

(b) A 5% solution of a high molecular weight, commercially available, oil-soluble sodium petroleum sulfonate was made in di-sec-butyl sebacate. The panels immersed in synthetic sea water were corroded at the end of twenty-four hours, but less so than the panels with the same sebacate without sulfonate. Panels subjected to test in the humidity cabinet were rusted in five to six days.

' (c) A solution of 5% of the same sulfonate and 0.5% of diisobutylphenoxy(ethoxy)lethanoi in disec-butyl sebacate was applied to steel panels which were immersed in the synthetic sea water bath. There was slight rusting at the end of twenty-four hours. Panels tested in the humidity cabinet were free of corrosion at the end of a week, when the tests were discontinued.

(d) A solution of 5% of the same sulfonate and 1% of diisobutylphenoxy (ethoxy) 4ethanol in disec-butyl sebacate was also appliedto steel panels. There were immersed in the synthetic sea water bath for twenty-four hours and were then examined. They were but very slightly corroded. Panels were also tested in the humidity cabinet and found free of all corrosion during the test period of 168 hours.

Example 3 (a) A 2.5% solution of a commercially available petroleum sulfonate showing an average molecular weight of about 550 was made in di-secbutyl sebacate. Steel panels were coated with this composition and hung in the humidity cabinet. Rusting had started within forty-eight hours. Other panels immersed in the synthetic sea water bath were badly corroded after twentyfour hours.

(b) A solution of 5% of the 550 molecular weight sulfonate and 0.5% of dodecylphenoxy- (ethoxy) lethanol in di-sec-butyl sebacate applied to steel panels gives protection against corrosion for over 168 hours. Panels coated with this solution show but a few rust spots after twenty-four hours of immersion in a synthetic sea water bath.

(0) A solution of 5% of the same sulfonate and 1% of the same ether alcohol used just above, when applied to steel panels, likewise gives over 168 hours of protection against moisture in a humidity cabinet. With the slight increase in concentration of ether alcohol, there is increased protection for panels immersed in synthetic sea water. v

Example 4 (a) Panels coated with di-2-ethylhexyl adipate begin to rust in one to three hours, whether in the humidity cabinet or in synthetic sea water.

(b) A solution of 5% of sodium, calcium, or barium petroleum sulfonates in di-2-ethylhexyl adipate gives greatly'increased protection under both conditions. For example, a 5% solution of a sodium petroleum sulfonate of molecular weight about five hundred allows but slight rusting of panels immersed in synthetic sea water.

e an (c) The addition to this solution of a 0.5% or v 1.0% of diisobutylphenoxy(ethoxy)iethanol,

CaH11C6H4OC2H4OC2H4OCaH4OCzH4OC2H4OI-I prevents corrosion within twenty-four hours.

\ Example 5 hours of immersion.

Example 6 Tests carried out with di-sec-butyl azelate in 0 the manner used in Examples 4 and 5 give similar results. The 5% sulfonate' solution on steel panels limits corrosion in the twenty-four hour immersion tests. he rusting of panels coated with a solution containing 5% of the sulfonate and 0.5% of diisobutylphenyl(ethoxy) lethanol in the di-sec-butyl azelate was limited to a few rust spots at the end of twenty-four hours. A solution of 5% of the sulfonate and 1% of the same ether alcohol in the same preparation of di-sec-butyl azelate effectively prevented any rust during twenty-four hours of immersion of panels in synthetic sea water.

Example 7 Tests comparable to those described in the examples above have been extensively carried out with di-Z-ethylhexyl sebacate, alone, with addition of petroleum sulfonates, and with addition of petroleum sulfonates and alkylphenoxy polyethoxyethanols. The results show that 1% or more of an oil-soluble sulfonate imparts some protective power against corrosion to moisture. The protective action is improved, however, upon addition of 0.5% to 2% of the polyethoxyethanols having three to five ether groups. These are all oil-soluble, water-insoluble ether alcohols. With more ether groups, water-solubility begins and the value of the alkylphenoxy polyethoxyethanols disappears. The ether alcohols as sole additives do not give anti-corrosive action. Improved re sistance to corrosionrequires that they be used in conjunction with an oil-soluble petroleum sulfonate. j

Example 8 A 1% solution of a commercial petroleum sulfonate with an average molecular weight between 550 and 600 was made in di-2-ethylhexyl sebacate. Steel panels coated therewith rusted after about eighty hours of exposure in the humidity cabinet at 120 F. and rusted badly within twenty-four hours of immersion in syntheticsea water. A 4% solution of the same lot of petroleum sulfonate and 1.5% of diisobutylcate. Panels coated withthis solution began to rust after about ninety hours in the humidity cabinet at 120 F. Coated panels immersed in the synthetic sea water bath rusted badly within twenty-four hours. The addition of 0.5% of diisobutylphenoxy(ethoxy)iethanol to this su1- fonate solution increased the period of protection in the humidity cabinet to one hundred hours. Panels coated with the solution of sulfonate and oil-soluble polyether alcohol in di-2-ethylhexyl sebacate were but very slightly rusted after immersion for twenty-four hours in synthetic sea water.

' Example 9 solution of. another commercial sodium phenoxy(ethcxy)4ethanol prevented corrosion of steel panels coated with this solution for 129 hours in the humidity cabinet at 120 F. There was very slight rusting of other panels coated with this solution after twenty-four hours of immersion in synthetic sea water. When the concentration of the diisobutylphenoxy(ethoxy)4 ethanol was raised to 2% with the sulfonate remaining at 4%, there was no rusting of immersed panels in twenty-four hours, but the rust resistance to moisture at 120 F. was not improved.

Example 1 0 A 4% solution of another petroleum sulfonate of molecular weight 550 to 600 and 0.5% of diisobutylphenoxy(ethoxy)methanol in di-2-ethylhexyl sebacate gave over a week's full protection for steel panels in the humidity cabinet at 120 F. and fair protection for steel panels immersed in synthetic sea water for twenty-four hours.

The addition of a polyethoxyethanol with three to five ether linkages to a 'diester solution of an oil-soluble petroleum sulfonate has an influence on the lubricating value of the resulting composition. For instance, a solution of 5% of a sodium petroleum sulfonate in di-2-ethy1hexyl adipate gave wear in a Falex tester at the rate of 8.1 milligrams loss per hour. Addition of 1% of diisobutylphenoxy(ethoxy)lethanol reduced the rate of wear to 5.5 milligrams per hour.

To the solutions described above, prepared from diesters of dicarboxylic acids of six to ten carbon atoms and aliphatic monohydric alcohols of four to fourteen carbon atoms, in which are dissolved an oil-soluble petroleum sulfonate and an oil-soluble valkylphenoxy polyethoxyethanol with three to five ether linkages, there may be added other substances which are soluble in the solutions and which act as wear-resisting agents, anti-oxidants, thickeners, extreme pressure agents, and the like. Thus, there may be used such compounds as diphenylamine, thiophosphites, salts of complex alkylhydroxybenzenes in which the phenyl rings are linked through sulfur, poly(aminomethyl) phenols, sulfurized unsaturated glyceride oils, aluminum, lithium, or calcium stearates, or other fatty acid soaps which form gels with the oily esters, etc.

We claim:

1. Composition of matter consisting essentially of a diester of a saturated aliphatic dioarboxylic acid of six to ten carbon atoms and an aliphatic monohydric alcohol of four to fourteen carbon atoms in which there is dissolved from 1% to 7.5% 'of an oil-soluble petroleum sulfonate and from 0.5% to 2% of an oil-soluble alkylphenoxypolyethoxyethanol having an alkyl group of four to twelve carbon atoms and having three to five ether linkages, the amount of diester, sulfonate, and alkylphenoxypolyethoxyethanoi totalling 100%.

2. The composition of claim 1 in which the concentration of said alkylphenoxypolyethoxyethanol does not exceed half of the concentration of the said sulionate.

3. A composition of matter consisting essentially of a diester of a saturated aliphatic .dicarboxylic acid ancla saturated aliphatic monohydrio alcohol of four to fourteen carbon atoms in 7 which there is dissolved from 2.5% to 6.5% of an oil-soluble salt of a petroleum sulfonic acid having a molecular weight from five hundred to seven hundred and from 0.5% to'2% of an oilso1ub1e alkylphenoxypolyethoxyethanol having an alkyl group of four-to fourteen carbon atoms and having three to five ether linkages, the concentration of said alkylphenoxypolyethoxyethanol not exceeding half the concentration of the said salt, the amount of diester, sulfonate, and a]kylphenoxypolyethoxyethanol totalling, 100%.

4. The composition of claim 3 in which the alkylphenoxypolyethoxyethanol contains five ether linkages.

5. The composition of claim 4 in which the alkyl group of the alkylphenoxypolyethoxyethanol contains eight carbon atoms.

6. The composition of claim 5 in which the diester is a dioctyl ester of sebacic acid.

7. A composition of matter consisting essentially of a diester of sebacic acid and a branched chain, saturated, aliphatic monohydric alcohol of four to fourteen carbon atoms having dissolved 8 therein from 2.5% to 6.5% or an oil-soluble petroleum suli'onate and from 0.5% to 2% or an oil-soluble octylphenoxyethoxyethoxyethanol, in a proportion which does not exceed half the concentration of the said sulfonate, the amount 01 REFERENCES CITED The following references are of record in'the file of this patent:

UNITED STATES PATENTS Name Date Bruson Mar. 30, 1937 Bruson Oct. 17, 1939 Duncan Oct. 8, 1946 Wasson Mar. 11, 1947 in which the di- Number 

